Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of a radio access technology (RAT) is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UTRAN utilizes a Wideband Code Division Multiple Access (W-CDMA) air interface. Another 3GPP standard is Global System for Mobile Communications (GSM) that supports a GSM EDGE Radio Access Network (GERAN). Other examples of RAT or standards include High Speed Packet Access (HSPA), CDMA2000, Wireless LAN (WLAN), Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX), etc.
Some wireless user equipment (UE) can support two or more RATs. For example, a UE may be equipped with multiple SIM cards to access multiple networks associated with different subscriptions. Some such devices can share transmission resources (e.g., modem, transceiver, RF front end, low noise amplifier, etc.) for accessing multiple networks simultaneously. One example of such UE is a dual-SIM dual active (DSDA) UE, which can be simultaneously active on two networks using the same or different RATs. Some DSDA devices have a single transmission (TX) chain, which is shared for accessing both networks simultaneously.